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AssigneeHoneywell Inc.
InventorRobert E. Bicking
Estimating the term…
A geartooth sensor is provided with a circuit which determined a threshold magnitude as a function of the minimum value of a first output signal from a magnetically sensitive component and an average output signal from a magnetic sensitive component. Circuitry is provided to determine the average signal. The minimum signal is then subtracted from the average signal and the resulting signal is doubled before being scaled by a predetermined fraction and then compared to the original output signal from the magnetically sensitive component. This circuit therefore determines a threshold signal as a function of both the minimum signal value and the average signal value and, in addition, enables the resulting signal to be scaled to a predetermined percentage of this difference for the purpose of selecting a threshold value that is most particularly suitable for a given application.
A magnetic sensor, comprising:
A magnetic sensor, comprising:
A magnetic sensor, comprising:
Dependencies are inferred from the claim text.
Error correction: correction of gain, threshold, offset or phase control
By measuring frequency of generated current or voltage: of pulse signals
Of pulse signals: delivered by variable reluctance detectors
With an adaptive threshold: modified by switching, e.g. by a periodic signal or by a signal in synchronism with the transitions of the output signal
Term ended 3 Mar 2015 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
1. Field of the Invention
The present invention is generally related to a geartooth sensor and, more particularly, to a geartooth sensor that measures the magnetic field strength imposed on a magnetically sensitive component and compares the magnetic field strength to a threshold that is calculated as a function of the minimum magnetic field strength and average magnetic field strength over a preselected period of time.
2. Description of the Prior Art
The present invention will be more fully and completely understood from a reading of the Description of the Preferred Embodiment in conjunction with the drawings, in which:
FIG. 1 illustrates a typical application of a geartooth sensor;
FIG. 2 illustrates the possible variability between the sizes and spacing of teeth and interstitial slots of a target;
Throughout the Description of the Preferred Embodiment of the present invention, like components will be identified by like reference numerals.
FIG. 1 illustrates a typical example of a geartooth sensor. A gear 10 is arranged for rotation about a central axis 12. A plurality of gearteeth 14 is attached to the gear for rotation through a detection zone of the geartooth sensor. The simplified schematic representation of the geartooth sensor in FIG. 1 comprises a magnet 16 and a magnetically sensitive component 18. The magnetically sensitive component 18 can be a Hall effect element or an arrangement of magnetoresistors. The specific configuration of the magnetically sensitive component 18 is not limiting to the application of the circuit of the present invention.
FIG. 2 is a simplified schematic of a target 20 which comprises a plurality of ferromagnetic members 22 that are spaced apart and separated by interstitial spaces 24. As can be seen in FIG. 2, the interstitial spaces 24 and the ferromagnetic members 22 vary in shape and size. Some of the ferromagnetic members 22 are larger than others and some of the interstitial spaces 24 are larger than others. For example, the interstitial space identified as G1 is much larger than interstitial space identified as G2. Because of the possible variation in size and spacing of the teeth, certain limitations are imposed on the ability of a geartooth sensor to accurately determine the presence and position of a geartooth within its detection zone. These problems will be described in greater detail below.
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